16.0 Cu. In. 3.5" dia. round fan support box for use with nonmetallic sheathed cable - Machine tapped fixture holes, rigid hard box construction, no distortion with high temperatures, shatter resistant with low temperatures - New work residential construction 2 HR fire resistive walls and ceilings (35 lbs. fan support and 50 lbs. fixture support) - Fiberglass reinforced polyester - thermoset box - Size: Depth=2 3/8", Dia=3 1/2" - Mount with Nail-on with fetter ring nails - Speed KlampsÖ factory installed